It’s a steamy July night in Bay Shore, and Main Street is closed to traffic and packed with people during the hamlet’s first Alive by the Bay festival. The temperature hovers in the mid-80s, and people are thirsty.

Usually, cold beer rules in such situations. However, inside Salt & Barrel, an elegant cocktail-and-seafood spot in the middle of town, the majority of glasses are instead filled with mounds of pink slush: frosé.

Frosé, a portmanteau for frozen rosé wine, is maybe the inevitable extension of unabated rosé fever, and made by combining rosé with a splash of spirits and sweetener into a slushie machine until it has the consistency of melting snow. As the days grew hotter, the phrase “rosé all day” morphed into “frosé all day,” at least in New York City, where frosé is as unstoppable as cold lava.

On Long Island, the places that carry it are fewer and farther between — American Beech in Greenport serves frosé — and Ryan Flynn, co-owner of Salt & Barrel, rolled out her version about a month ago.

Already, it’s become a Salt & Barrel mainstay. “We launched it on a Friday, and sold 100 the first day,” said Flynn, who co-owns the restaurant with her brother Morgan Flynn, dad Jim Flynn and Danielle Grosseto. “And then we ran out in two weeks.”

When they did, they refilled their slushie machine with rum and ginger beer for a frozen version of the Dark & Stormy, but frosé is back in circulation. For their version, the Salt & Barrel team combines French rosé with Core Vodka, lemon juice and strawberry syrup, then lets the mixture twirl all night. “The more it turns and blends, the better the flavors. It brings out the sweetness of the fruit and tames the alcohol flavor,” Ryan Flynn said.

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The resulting drink — $7 during happy hour, $12 otherwise — is served in dainty gold-rimmed coupes, and possesses the spicy and floral notes of rosé, the texture of a 7-Eleven Slurpee and the hue of the moment: millennial pink.

The Flynns also own Flynn’s on Fire Island, where frozen rum-laced Rocket Fuels are the longtime signature drink. “The frosé is our Bay Shore Rocket Fuel,” Flynn said of this cocktail that’s sating, strong, emblematic of summer and a social-media darling all at once.